A photomechanical process includes a step for converting a continuous tone original image into a half-tone dot image. To this step, an infectious developing technique has been applied as a technique capable of reproducing a super-hard contrast image.
A lithographic type silver halide photographic light sensitive material to be treated in an infectious development process is comprised of, for example, a silver chlorobromide emulsion having an average grain size of 0.2 .mu.m, a narrow grain distribution, a uniform grain configuration, and a high silver chloride content in a proportion of not less than 50 mol % at least. When the lithographic type silver halide photographic light sensitive material is processed with an alkaline hydroquinone developer having a low sulfite ion concentration, that is so-called a lith type developer, an image high in contrast, sharpness and resolving power can be provided.
However, these lith type developers are seriously deteriorated in preservability, because it is liable to be air-oxidized. Therefore, a development quality can hardly be kept instant also in a repetition use.
There is a known method in which an image having a high contrast can rapidly be obtained without making use of the above-mentioned lith type developer. For example, as appeared in Japanese Patent Publication Open to Public Inspection--hereinafter referred to as JP OPI Publication--No. 56-106244/1981, the method is that a hydrazine derivative is contained in a silver halide light sensitive material. According to this method, an extreme high contrast image can be obtained by processing with a well preservable and rapidly processable developer.
In the above-mentioned technique, a developer having a high pH of not lower than pH 11.0 is required to be used for satisfactorily displaying the high contrast property of hydrazine derivatives. In such developers having a high pH of not lower than 11.0, the developing agents thereof are liable to be oxidized when they are exposed to the air, though they are rather stable than the lith type developers. When the developing agents are oxidized, there may frequently be some instances where an extreme high contrast image may not be obtained.
For overcoming the above-described defects, JP OPI Publication No. 63-29751/1988 and European Patent Nos. 333,435 and 345,025 disclose the silver halide photographic light sensitive materials each containing a contrast raising agent capable of making a contrast higher even in a developer having a comparatively lower pH.
However, when the silver halide photographic light sensitive material containing such a contrast raising agent as mentioned above is processed with the developer having a pH of lower than pH 11.0, the high-contrast results are not satisfactory and any satisfactory half-tone characteristics cannot be obtained, which have been the present situations.